Means for controlling movements of valves or other elements



Patented May 9, 1944 MEANS FOR CONTROLLING MOVEMENTS OF VALVES OR OTHER ELEMENTS Stanley Hedgecoek, London, England, assignor to Laystall Engineering Company Limited,

London, England Application October 9, 1941, Serial No. 414,388 In Great Britain July 2, 1941 9 Claims.

This invention relates to the control of sliding valves and other elements which are actuated by a force acting in opposition to loading means provided for the valve or the like, the loading means being of a nature such that a progressively increasing effort has to be appliedby the actuating means as the valve or the like is further displaced. Such a loading may comprise a spring means or a iiuid buffer, the invention being principally concerned however with spring loading arrangements; the actuating means may be any force such as, in the case of a valve, effort mechanically applied from a centrifugal governor or fluid pressure or suction.

Although it is necessary for the loading means to impose a resistance such that a predetermined actuating eiTort has to be applied in order to eliect initial movement of the valve or the like, it is sometimes an objection that the actuating eiort has to be progressively increased in correspondence with further movement.

The present invention has in view to overcome the above objection and provides a loading means of a nature such that after having obtained a predetermined extent of movement of the actuated member by applying a sucient actuating force, the actuated member can be further moved without having to increase the applied ellort at the original rate, or (depending upon the design adapted) can be maintained in the position then assumed or be further operated by the application of decreased effort, as distinct from a lower rate of increase.

The invention provides a method of controlling a sliding valve or other actuated member, Which consists in loading same by a primary loading means, and by a weaker secondary loading means, providing a means for resisting the deiiection of said secondary loading means whilst the primary loading means is overcome during ai predetermined extent of movement of the valve or the like, and then automatically releasing the said resisting means associated with the secondary loading means thereby to allow said secondary loading means to be overcome either in allowing the primary spring to exert itself and/or in permitting the actuated member to have further movement without increasing the loading of the primary loading means.

The invention is primarily concerned with an apparatus in' which the primary and secondary loading means consist of springs, but nevertheless is applicable to arrangements wherein one oreach of the primary and secondary loading hydraulic) of such a nature that a progressively increasing effort needs to be applied t0 OVeI- come same. In the preferred case where spring means is employed a convenient arrangement is to provide primary and secondary compression springs acting on opposite sides of a floating member. In this case the resisting means assoeiated with the secondary spring is of such a form that said floating member is prevented from having substantial movement with respect to the actuated member until the primary spring has been compressed to a predetermined extent, the said primary spring bearing against any suitable stationary member. The actuated member may incorporate a sleeve-like portion in which the oating member is freely mounted, said sleevelike portion beingadapted to house the primary and secondary springs. The resisting means associated with thesecondary spring may consist of a fluid chamber in which fluid is trapped until released when the said secondary spring is to come into action, or any suitable mechanical device may be provided for spacing the floating member from the actuated member to prevent compression of said secondary spring until same is required to come into action, any suitable mechanical means being provided for displacing said spacing device.

In order that the invention may be readily understood reference is directed to the accompanying drawing, wherein:

Figures l, 2 and 3, ...are sectional views of a control device according to one embodiment of the invention and showing the component parts in the dilerent relative positions taken up during operation,

Figures 4 and 5 are similar views of a modiiication, and

Figures 6, 7 and 8 are sectional views of a control device constructed according to another embodiment of the invention.

In each of the embodiments illustrated, the stem 8 of a valve or other actuated member is provided Awith a cylindrical sleeve-like extension 9 adapted to slide in the bore I0 of a body II. If `the actuated member is a valve, said extension 9 may be adapted to control the opening of ports I2. In the said sleeve 9 there is freely mounted a floating bush I3 which divides the extension into primary and secondary chambers. On the opposite sides of said bush bear a primary compression spring I 4 and a weaker secondary spring I5, the distant end of the primary springbearing against a stationary base member means is some'other force (e. g..pneumatic or 65 I 6 which has a loose nt in the sleeve 9 whilst `l jecting pin 2I adapted, when the bush I3 reaches a predetermined position with respect'to thelsaidy base member I5, to contact with and open the ball valve I9 as later explained. The sleeve Sis peripherally recessed from its end to forma chan nel 22 between said sleeve 9 and the body I I, and orifices 23 formed through the wall of the sleeve 9 establish communication between thechannel 5 22 and the chamber 24 behind the bush I3 when the actuated member 3 is in its normal posi'-v tionythat -is to say, the position in whichthe said member 8 is closing the ports I2 (Figi. l). The entire space contained within the bore III` and within the extension 9 of member 8 and which comprises the chamber 24, the chamber enclosing spring I4, the central bore I5, the channel 22and the orifices 23, is completely filled with oil or other-liquid.

, Dealing now'with the operation of the device, and assuming that the actuated member 8 is be ing, opened from a normal position which is such that.y the said member 8 is closing the ports I2 (Fig-` l), the orifices 23 allow escape of liquid from the chamber 24 during the first fraction of movement ofthe actuated member, the secondary spring I becoming very slightly compressed. The floating bush I3 now substantially closes the orifices 23 and owing to liquid escape from chamber 2li being now prevented, the said chamber constitutes a builer between the saidfloating bush and the actuating member causing the latterto'move said bush substantially in unison with itself. Thus, during further movement of the member 8, the primary spring Ill will be compressed, whereas the buffer prevents the weaker secondary spring I5 being-overcome. Loading of theprimary spring continues until the actuated member '8 reaches such a position that the fixed pin 2I contacts with the ball valve I9; further movement beyond thispoint results in the pin depressing and opening the ball valve (Figure 2), with consequential escapeof vliquid from the chamber 2I3. In consequence the fioating bush I3 hovers in the proximity of the said position and the primary spring I4 remains loaded to the same extent, the secondary spring I5 becoming deflected during the continued movement of the actuated member.

From the above description it will follow that the actuating force necessary to move the actuated member from the position shown in Figure .2 to the limit of its movement (Fig. 3) is the force necessaryto maintain the loading of the primary spring I4 plus the effort necessary to overcome the weaker secondary spring I5. Thus the continued movement is obtained without having to increase the vactuating veffort at the originalfrate, i,.Duringreturn of the member 8 effected by the loaded springs I4 and I5,.automatic depression of theball valve. I9 results in the replacement .of liquid in chamber 2li. Y

In the modied construction shown in Figures il and` 5 there is provision for allowing the .pri-

mary spring to expand. after having'- been com'- When the primary spring III has been comvrpressed to a predetermined extent, such that the pin-2| contacts with the ball valve I9 as above explained, a very slight further movement of the I actuatedmember B (the extent of which will depend on the position of the recess 25) will result in the orifices 23 coming into register with the precess25. This provides escape from the buffer 1 'chamber 2li such as will allow the floating bush IIBto travel backwards with consequent expansion of the primary spring and loading of the secondary spring instead. Owing to such expansionof the primary. spring the actuated memberismaintainedin its eventual position'by apressure lower than that which was required to loperate same. i In the apparatus shown in Figures 6, I and 8` a mechanical spacing element is provided instead of a liquid buier for resisting the deflection of the secondary spring. Accordingly in this case there is no need for the components to beimmersed in oil. Thesaid spacing elementV in the example shown consists of a disc 2'I from which extends an inclined tube 28, the passage within said tube having a cam face 29 attheend o the tube. Y l

Whenthe actuated member 8a is in normal position Fig. 6, i. e; when the actuated member is closing the ports I2, the secondary spring I5 by bearing on the ydisc 2'I brings same into a position in which the tube 28 is out of alignmentwith the bore I8 in the floating bush 2I3. Consequently, when the member 8a commences to move, the tube v28 abutsthebush 2I3 and functions as a spacing element to .compel the bush to move as aunit vwith the said member 8a. Thus the primary spring I4 is compressed but deflection of the'secondary spring is prevented during a predetermined extent of movement'of member 8a. The 'pin 2I is so positioned that .at therequired moment it will engage the. cam face 29 of the tube 28 (Fig. 7), the cam face being so shaped that'further movement of member Ba will result in the tube 28 being laterally displaced and coming into alignment with the bore I3 in the bush, whereby said tube enters and slides into the said bore I8 (Fig. 8). Owing to the tube 2B no longer serving as a spacing element, the primary, spring I4 isable to exert` itself indisplacingltheat'- ing bush 2I3, and consequently aireducediapplied 'force will serve to maintain theactuated member 8a in the position now reached. orywill serve for further movementrof said member. .g

Iclaim:

1. Means for controlling the movement oan actuated member, comprising, a body. having .a guiding bore, a stationary't base insaid I bore, a

tubular V'extension-'Fior saidactuated member` Slide'V able insaid bore, floating member mountedlto move within said extensiorilwith-respectto.said actuated member, and dividing'jsaid V.e'z'xtensionl in to primary and lsecondary chambers; primary and secondary loading means. respectivelylllocated in said Ychambers and acting inopposite directions .on saidfloating member, both loading mean'sf cooperating with said V-basetoresist ac-A mating effort applied to said actuated member, said primary loading means being of greater strength than the secondary loading means and imposing resistance on .the actuated member which progressively increases with increased deflection thereof, resistance means between the actuated member and the floating member for restraining substantial displacement of the floating member relative to the actuated member such as would permit deflection of the secondary loading means while the primary loading means is being deflected during the initial period of movement of the actuated member, and means for releasing said resistance means after a pre-determined degree of deflection of said primary loading means.

2. Means for controlling the movement of an actuated member, according to claim 1, wherein the primary and secondary loading means comprise, compression springs of different strengths acting on opposite sides of the floating member, one of said springs bearing against the actuated member while the other bears against said stationary base. i

3. Means for controlling the movement of an actuated member, according to claim 1, wherein the chambers on opposite sides of the floating member are filled with liquid and the resistance means for restraining the deflection of the secondary spring comprises a liquid buffer provided by said liquid in the secondary chamber and the floating member which is provided with a spring seated valve, and means for opening said valve to release the liquid pressure from the secondary chamber when the primary spring has been deflected to a predetermined extent.

4. Means for controlling the movement of an actuated member, according to claim 1, wherein the primary and secondary chambers are filled with liquid and the resistance means comprises a liquid buffer provided by liquid in said secondary chamber and the floating member, normally closed valve means on the floating member, and a pin projecting from said stationary member adapted to unseat said valve as the floating member moves relative to the stationary member, the arrangement being such that during continued movement of the actuated member, the floating member hovers in a position in which the extent of loading of the primary spring is maintained substantially constant.

5. Means for controlling the movement of a sliding valve with respect to a radially disposed Valve orifice, comprising, a body having a guiding bore, a stationary base in the bore, a tubular extension for said sliding valve slidable in said bore, said tubular extension being formed with two external surfaces of different diameter, one of said surfaces closely fitting the bore and the other being spaced therefrom, the space defined by the guiding bore, extension, and said base being filled with liquid, port means in the wall of the tubular member at the junction of said external surfaces of different diameter, a floating bushing slidable within the tubular extension and having a central passage, a primary spring confined between the stationary base and one side of the floating member, a secondary spring of weaker strength than the primary spring confined between the floating member and the actuated member, a normally closed spring pressed valve within the central passage of the floating member, a pin extending from the stationary base in the path of movement of said valve on the iloating member and adapted to unseat said valve to release pressure of liquid trapped. in the resistance chamber which houses a secondary spring. j Y

6. Means for controlling the movement cfa sliding valve with respect to a radially disposed valve orifice, comprising, a body having alguiding bore, a tubular extension for said sliding valve slidable in said bore, said extension having a portion of its exterior in close sliding relation to the bore andalso having its remaining portion of less diameter than the bore and provided with lateral ports at the junction of said latter portion with said first mentioned portion, a floating member having a central passage and also having a peripheral recess connected by an oblique duct with the'central passage, a stationary base within the bore, the space defined by the guiding bore, extension, and said base being filled with liquid, a primary spring confined between the stationary base and one side of the floating member, a secondary spring of less strength than the primary spring conned between the other side of the floating member and said sliding valve, a spring pressed valve normally closing the central passage of the floating member, and a pin projecting from said stationary member and adapted to engage and unseat said valve when the primary spring is deflected sufficiently by the floating member to bring the valve of said floating member into engagement with the pin, thereby'releasing liquid trapped at the side of the floating member at which the secondary spring is located.

7. Means for controlling the movement of an actuated member, according to claim 1, wherein the resistance means for restraining deflection of the secondary spring comprises, a mechanical spacing element normally located in the secondary chamber and held between the actuated member and the floating member, and means for mechanically displacing said spacing element relative to the floating member when the primary spring has been deflected to a predetermined extent.

8. Means for controlling the movement of an actuated member, according to claim 1, wherein the floating member has a central passage and moves substantially in unison with the actuated member during deflection of the primaryfspring and the said resistance means is in the form of a mechanical spacing element located in the secondary chamber, said element consisting of a base flange and a tubular portion whose axis is oblique to the axis of the flange, the mouth of said tubular portion being internally tapered to provide a cam face, the flange of said spacing element normally engaging the actuated member and the opposite end having the cam face normally engaging the floating member to resist deflection of the secondary spring, and a pin projecting from said stationary member and passing through the central passage of the floating member to engage the cam face of the spacing element and rock said element so that the said tubular portion can move into the said central passage of the oating member.

9. Means for controlling the movement of a sliding valve with respect to a valve orifice, comprising, a body having a guiding bore, a tubular extension for said member slidable in said bore, a stationary base in the bore at a point beyond the limit of movement of the sleeve therein, a floating member having a central passage and slidable within the tubular extension, a primary spring confined between the stationary base and one side of the floating member. a secondary springy weaker than theprmary spring located at the other side of the floating' member", a spacing element including a base flange vand a tubular sleeve .Whose axisls voblique to the axis of the flange and having an internal cam face, said .will initially move the oatin'g member to com'- press the primary spring while the secondary spring remains incompressed, and means on the stationary base for engaging the cam surface of the sleeve of the resistance member to rock the same on its base flange and cause saidl sleeve to disengage the .floating member and telescope -withinthe central passage thereof, whereby, continued movementof the sliding valve and the pr- -mary spring will tend to collapse the secondary spring. Y

- STANLEY HEDGECOCK. 

